Objectives: The biomechanical assessment of spasticity has been developed recently, but not standardized yet for the test procedures and parameters of measurement. This study was designed for the development of standardized method of the biomechanical assessment of spasticity using the isokinetic dynamometer.

Method
The plantar flexor muscles of both ankles were stretched from 40^o plantar flexion to 20^o dorsiflexion using the isokinetic dynamometer at the angular velocities of 15^o, 30^o, 60^o, 90^o, 120^o, 180^o, and 300^o per second. Three parameters, peak eccentric torque(PET), torque threshold angle(TTA), and angle at peak torque(PTA) were analysed.

Results
PET increased and TTA decreased significantly in the involved side. The side to side difference of PET and TTA increased in the patient group with more spasticity. The side to side difference of PET increased, but the side to side difference of TTA decreased with the increase in the angular velocity.

Conclusions
The isokinetic dynamometer is useful in the assessment of the spasticity of ankle plantar flexor of hemiplegic patients. PET and TTA are useful parameters. The faster angular velocities seemed to be more appropriate for the analysis of torque values and the slower angular velocities seemed to be more appropriate for the analysis of thresholds.